File espos_onewire.h¶

FileList > espos_sensors > include > espos_onewire.h

#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include "esp_err.h"

Public Types¶

Type	Name
typedef struct espos_ds18b20 *	espos_ds18b20_handle_t
typedef struct espos_onewire_bus *	espos_onewire_bus_handle_t

Public Functions¶

Type	Name
uint64_t	espos_ds18b20_address (espos_ds18b20_handle_t dev) The sensor's ROM id.
void	espos_ds18b20_close (espos_ds18b20_handle_t dev)
uint32_t	espos_ds18b20_convert_ms (int bits)
esp_err_t	espos_ds18b20_open (espos_onewire_bus_handle_t bus, uint64_t addr, espos_ds18b20_handle_t * out) Open one sensor by address.
esp_err_t	espos_ds18b20_read_kelvin (espos_ds18b20_handle_t dev, float * out_kelvin) The temperature from the LAST conversion, in kelvin the Signal K unit, so nothing downstream has to convert.
esp_err_t	espos_ds18b20_set_resolution (espos_ds18b20_handle_t dev, int bits) Resolution, 9..12 bits.
void	espos_onewire_close (espos_onewire_bus_handle_t bus)
esp_err_t	espos_onewire_convert_all (espos_onewire_bus_handle_t bus) Start a conversion on every sensor on the bus at once (the 1-Wire SKIP ROM broadcast), then read each one when it is done.
esp_err_t	espos_onewire_open (int gpio, espos_onewire_bus_handle_t * out) Open a 1-Wire bus on one GPIO.
esp_err_t	espos_onewire_search (espos_onewire_bus_handle_t bus, uint64_t * addrs, size_t max, size_t * out_n) Find every DS18B20 on the bus.

Public Types Documentation¶

typedef espos_ds18b20_handle_t¶

typedef struct espos_ds18b20* espos_ds18b20_handle_t;

typedef espos_onewire_bus_handle_t¶

typedef struct espos_onewire_bus* espos_onewire_bus_handle_t;

Public Functions Documentation¶

function espos_ds18b20_address¶

The sensor's ROM id.

uint64_t espos_ds18b20_address (
    espos_ds18b20_handle_t dev
)

function espos_ds18b20_close¶

void espos_ds18b20_close (
    espos_ds18b20_handle_t dev
)

function espos_ds18b20_convert_ms¶

uint32_t espos_ds18b20_convert_ms (
    int bits
)

function espos_ds18b20_open¶

Open one sensor by address.

esp_err_t espos_ds18b20_open (
    espos_onewire_bus_handle_t bus,
    uint64_t addr,
    espos_ds18b20_handle_t * out
)

Address 0 means "the only sensor on the bus" and is a convenience for the single-sensor case; it fails when the bus has more than one, rather than picking one at random.

function espos_ds18b20_read_kelvin¶

The temperature from the LAST conversion, in kelvin the Signal K unit, so nothing downstream has to convert.

esp_err_t espos_ds18b20_read_kelvin (
    espos_ds18b20_handle_t dev,
    float * out_kelvin
)

Does not trigger one: call espos_onewire_convert_all() and read after the conversion time.

A sensor that has been unplugged reads 85 C exactly (the chip's power-on value) and that is reported as ESP_ERR_INVALID_RESPONSE rather than a plausible-looking number, because a disconnected engine sensor reading a steady 85 C is the kind of fault that gets believed.

function espos_ds18b20_set_resolution¶

Resolution, 9..12 bits.

esp_err_t espos_ds18b20_set_resolution (
    espos_ds18b20_handle_t dev,
    int bits
)

Fewer bits convert faster: 9 bits is 0.5 C in ~94 ms, 12 bits is 0.0625 C in ~750 ms. For a cabin or engine temperature 10 or 11 bits is the sensible trade; 12 is the chip default.

function espos_onewire_close¶

void espos_onewire_close (
    espos_onewire_bus_handle_t bus
)

function espos_onewire_convert_all¶

Start a conversion on every sensor on the bus at once (the 1-Wire SKIP ROM broadcast), then read each one when it is done.

esp_err_t espos_onewire_convert_all (
    espos_onewire_bus_handle_t bus
)

This is the pattern to use: converting sensors one at a time costs the conversion time PER sensor, so eight sensors at 12 bits take six seconds instead of one.

espos_ds18b20_convert_ms() is how long to wait before reading.

function espos_onewire_open¶

Open a 1-Wire bus on one GPIO.

esp_err_t espos_onewire_open (
    int gpio,
    espos_onewire_bus_handle_t * out
)

function espos_onewire_search¶

Find every DS18B20 on the bus.

esp_err_t espos_onewire_search (
    espos_onewire_bus_handle_t bus,
    uint64_t * addrs,
    size_t max,
    size_t * out_n
)

Fills addrs with up to max ROM ids and writes how many were found to *out_n. Log these once and put them in the configuration: an address is what a sensor IS, and it is printed as 16 hex digits.

The documentation for this class was generated from the following file espos_sensors/include/espos_onewire.h